This just sounds like you need to adjust the amplitude or brightness parameters properly. The tremulant waveforms are used with St. Anne's but had modifications to these settings to get the proper results. Note that using a non-reed tremulant waveform for a reed rank isn't really ideal, you typically will want to use a similar family of ranks for the tremulant waveforms to match with.
You can also view the settings for the tremulants provided in the example CODM files which use the St. Anne's ranks and use these as a basis to go from.